Twin doctors Chris and Xand van Tulleken set out to explore whether the decline in children's freedom is affecting their ability to learn the skills they need for healthy development. We meet Michi, a seven year-old living in Tokyo who commutes across the city completely alone to get to school. Inspired by his independence, the van Tulleken's challenge a group of British children aged four-seven years old to travel across London and catch a bus to the London Eye - all without their parents.